[Backport 2.x] Fix shard level rescoring disabled setting flag

CHANGELOG.md

@@ -26,6 +26,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 * Fixing the bug when a segment has no vector field present for disk based vector search (#2282)[https://github.com/opensearch-project/k-NN/pull/2282]
 * Allow validation for non knn index only after 2.17.0 (#2315)[https://github.com/opensearch-project/k-NN/pull/2315]
 * Release query vector memory after execution (#2346)[https://github.com/opensearch-project/k-NN/pull/2346]
+* Fix shard level rescoring disabled setting flag (#2352)[https://github.com/opensearch-project/k-NN/pull/2352]
 ### Infrastructure
 * Updated C++ version in JNI from c++11 to c++17 [#2259](https://github.com/opensearch-project/k-NN/pull/2259)
 * Upgrade bytebuddy and objenesis version to match OpenSearch core and, update github ci runner for macos [#2279](https://github.com/opensearch-project/k-NN/pull/2279)

src/main/java/org/opensearch/knn/index/KNNSettings.java

@@ -577,7 +577,7 @@ public static Integer getFilteredExactSearchThreshold(final String indexName) {
             .getAsInt(ADVANCED_FILTERED_EXACT_SEARCH_THRESHOLD, ADVANCED_FILTERED_EXACT_SEARCH_THRESHOLD_DEFAULT_VALUE);
     }
 
-    public static boolean isShardLevelRescoringEnabledForDiskBasedVector(String indexName) {
+    public static boolean isShardLevelRescoringDisabledForDiskBasedVector(String indexName) {
         return KNNSettings.state().clusterService.state()
             .getMetadata()
             .index(indexName)

src/main/java/org/opensearch/knn/index/query/nativelib/NativeEngineKnnVectorQuery.java

@@ -63,11 +63,11 @@ public Weight createWeight(IndexSearcher indexSearcher, ScoreMode scoreMode, flo
         if (rescoreContext == null) {
             perLeafResults = doSearch(indexSearcher, leafReaderContexts, knnWeight, finalK);
         } else {
-            boolean isShardLevelRescoringEnabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(knnQuery.getIndexName());
+            boolean isShardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(knnQuery.getIndexName());
             int dimension = knnQuery.getQueryVector().length;
-            int firstPassK = rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension);
+            int firstPassK = rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension);
             perLeafResults = doSearch(indexSearcher, leafReaderContexts, knnWeight, firstPassK);
-            if (isShardLevelRescoringEnabled == true) {
+            if (isShardLevelRescoringDisabled == false) {
                 ResultUtil.reduceToTopK(perLeafResults, firstPassK);
             }
 

src/main/java/org/opensearch/knn/index/query/rescore/RescoreContext.java

@@ -61,17 +61,17 @@ public static RescoreContext getDefault() {
      * based on the vector dimension if shard-level rescoring is disabled.
      *
      * @param finalK The final number of results to return for the entire shard.
-     * @param isShardLevelRescoringEnabled A boolean flag indicating whether shard-level rescoring is enabled.
-     *                                     If true, the dimension-based oversampling logic is bypassed.
+     * @param isShardLevelRescoringDisabled A boolean flag indicating whether shard-level rescoring is disabled.
+     *                                     If false, the dimension-based oversampling logic is bypassed.
      * @param dimension The dimension of the vector. This is used to determine the oversampling factor when
      *                  shard-level rescoring is disabled.
      * @return The number of results to return for the first pass of rescoring, adjusted by the oversample factor.
      */
-    public int getFirstPassK(int finalK, boolean isShardLevelRescoringEnabled, int dimension) {
+    public int getFirstPassK(int finalK, boolean isShardLevelRescoringDisabled, int dimension) {
         // Only apply default dimension-based oversampling logic when:
         // 1. Shard-level rescoring is disabled
         // 2. The oversample factor was not provided by the user
-        if (!isShardLevelRescoringEnabled && !userProvided) {
+        if (isShardLevelRescoringDisabled && !userProvided) {
             // Apply new dimension-based oversampling logic when shard-level rescoring is disabled
             if (dimension >= DIMENSION_THRESHOLD_1000) {
                 oversampleFactor = OVERSAMPLE_FACTOR_1000;  // No oversampling for dimensions >= 1000

src/test/java/org/opensearch/knn/index/KNNSettingsTests.java

@@ -163,15 +163,15 @@ public void testGetEfSearch_whenEFSearchValueSetByUser_thenReturnValue() {
     }
 
     @SneakyThrows
-    public void testShardLevelRescoringEnabled_whenNoValuesProvidedByUser_thenDefaultSettingsUsed() {
+    public void testShardLevelRescoringDisabled_whenNoValuesProvidedByUser_thenDefaultSettingsUsed() {
         Node mockNode = createMockNode(Collections.emptyMap());
         mockNode.start();
         ClusterService clusterService = mockNode.injector().getInstance(ClusterService.class);
         mockNode.client().admin().cluster().state(new ClusterStateRequest()).actionGet();
         mockNode.client().admin().indices().create(new CreateIndexRequest(INDEX_NAME)).actionGet();
         KNNSettings.state().setClusterService(clusterService);
 
-        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(INDEX_NAME);
+        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(INDEX_NAME);
         mockNode.close();
         assertFalse(shardLevelRescoringDisabled);
     }
@@ -192,7 +192,7 @@ public void testShardLevelRescoringDisabled_whenValueProvidedByUser_thenSettingA
 
         mockNode.client().admin().indices().updateSettings(new UpdateSettingsRequest(rescoringDisabledSetting, INDEX_NAME)).actionGet();
 
-        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(INDEX_NAME);
+        boolean shardLevelRescoringDisabled = KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(INDEX_NAME);
         mockNode.close();
         assertEquals(userDefinedRescoringDisabled, shardLevelRescoringDisabled);
     }

src/test/java/org/opensearch/knn/index/query/nativelib/NativeEngineKNNVectorQueryTests.java

@@ -183,7 +183,7 @@ public void testRescoreWhenShardLevelRescoringEnabled() {
         ) {
 
             // When shard-level re-scoring is enabled
-            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(any())).thenReturn(true);
+            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(any())).thenReturn(false);
 
             // Mock ResultUtil to return valid TopDocs
             mockedResultUtil.when(() -> ResultUtil.resultMapToTopDocs(any(), anyInt()))
@@ -265,7 +265,7 @@ public void testRescore() {
         ) {
 
             // When shard-level re-scoring is enabled
-            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringEnabledForDiskBasedVector(any())).thenReturn(true);
+            mockedKnnSettings.when(() -> KNNSettings.isShardLevelRescoringDisabledForDiskBasedVector(any())).thenReturn(false);
 
             mockedResultUtil.when(() -> ResultUtil.reduceToTopK(any(), anyInt())).thenAnswer(InvocationOnMock::callRealMethod);
             mockedResultUtil.when(() -> ResultUtil.resultMapToDocIds(any(), anyInt())).thenAnswer(InvocationOnMock::callRealMethod);

src/test/java/org/opensearch/knn/index/query/rescore/RescoreContextTests.java

@@ -16,23 +16,23 @@ public void testGetFirstPassK() {
         float oversample = 2.6f;
         RescoreContext rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();
         int finalK = 100;
-        boolean isShardLevelRescoringEnabled = true;
+        boolean isShardLevelRescoringDisabled = false;
         int dimension = 500;
 
         // Case 1: Test with standard oversample factor when shard-level rescoring is enabled
-        assertEquals(260, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(260, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 2: Test with a very small finalK that should result in a value less than MIN_FIRST_PASS_RESULTS
         finalK = 1;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 3: Test with finalK = 0, should return MIN_FIRST_PASS_RESULTS
         finalK = 0;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 4: Test with finalK = MAX_FIRST_PASS_RESULTS, should cap at MAX_FIRST_PASS_RESULTS
         finalK = MAX_FIRST_PASS_RESULTS;
-        assertEquals(MAX_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MAX_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
     }
 
     public void testGetFirstPassKWithDimensionBasedOversampling() {
@@ -42,44 +42,44 @@ public void testGetFirstPassKWithDimensionBasedOversampling() {
         // Case 1: Test no oversampling for dimensions >= 1000 when shard-level rescoring is disabled
         dimension = 1000;
         RescoreContext rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensuring dimension-based logic applies
-        assertEquals(100, rescoreContext.getFirstPassK(finalK, false, dimension));  // No oversampling
+        assertEquals(100, rescoreContext.getFirstPassK(finalK, true, dimension));  // No oversampling
 
         // Case 2: Test 2x oversampling for dimensions >= 768 but < 1000 when shard-level rescoring is disabled
         dimension = 800;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure previous values don't carry over
-        assertEquals(200, rescoreContext.getFirstPassK(finalK, false, dimension));  // 2x oversampling
+        assertEquals(200, rescoreContext.getFirstPassK(finalK, true, dimension));  // 2x oversampling
 
         // Case 3: Test 3x oversampling for dimensions < 768 when shard-level rescoring is disabled
         dimension = 700;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure previous values don't carry over
-        assertEquals(300, rescoreContext.getFirstPassK(finalK, false, dimension));  // 3x oversampling
+        assertEquals(300, rescoreContext.getFirstPassK(finalK, true, dimension));  // 3x oversampling
 
         // Case 4: Shard-level rescoring enabled, oversample factor should be used as provided by the user (ignore dimension)
         rescoreContext = RescoreContext.builder().oversampleFactor(5.0f).userProvided(true).build();  // Provided by user
         dimension = 500;
-        assertEquals(500, rescoreContext.getFirstPassK(finalK, true, dimension));  // User-defined oversample factor should be used
+        assertEquals(500, rescoreContext.getFirstPassK(finalK, false, dimension));  // User-defined oversample factor should be used
 
         // Case 5: Test finalK where oversampling factor results in a value less than MIN_FIRST_PASS_RESULTS
         finalK = 10;
         dimension = 700;
         rescoreContext = RescoreContext.builder().userProvided(false).build();  // Ensure dimension-based logic applies
-        assertEquals(100, rescoreContext.getFirstPassK(finalK, false, dimension));  // 3x oversampling results in 30
+        assertEquals(100, rescoreContext.getFirstPassK(finalK, true, dimension));  // 3x oversampling results in 30
     }
 
     public void testGetFirstPassKWithMinPassK() {
         float oversample = 0.5f;
         RescoreContext rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();  // User provided
-        boolean isShardLevelRescoringEnabled = false;
+        boolean isShardLevelRescoringDisabled = true;
 
         // Case 1: Test where finalK * oversample is smaller than MIN_FIRST_PASS_RESULTS
         int finalK = 10;
         int dimension = 700;
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
 
         // Case 2: Test where finalK * oversample results in exactly MIN_FIRST_PASS_RESULTS
         finalK = 100;
         oversample = 1.0f;  // This will result in exactly 100 (MIN_FIRST_PASS_RESULTS)
         rescoreContext = RescoreContext.builder().oversampleFactor(oversample).userProvided(true).build();  // User provided
-        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringEnabled, dimension));
+        assertEquals(MIN_FIRST_PASS_RESULTS, rescoreContext.getFirstPassK(finalK, isShardLevelRescoringDisabled, dimension));
     }
 }